Spectroscopic analysis is popular method for determining compositions of fluids and other materials in a laboratory environment. However, implementing spectroscopic analysis in a downhole tool is a difficult task due to a number of obstacles, not the least of which is the great range of operating temperatures in which the tool must operate. If such obstacles were adequately addressed, a downhole optical radiometry tool could be used to analyze and monitor different properties of various fluids in situ.
For example, when formation fluid sampling tools draw fluid samples there is always a question of how much contamination (e.g., from drilling fluid in the borehole) exists in the sample stream and how much pumping must be done before the contamination level drops to an acceptable level. A downhole optical radiometry tool can measure various indicators of contamination, identify trends, and determine a completion time for the sampling process. Further, the downhole optical radiometry tool could be used to characterize the fluid composition to measure, e.g., water, light hydrocarbons, a distribution of hydrocarbon types (e.g., the so-called SARA measurement of saturated oils, aromatics, resins, and asphaltenes), H2S concentrations, and CO2 concentrations. Moreover, PVT properties can be predicted, e.g., by measurements of Gas-Oil Ratios. The fluid compositions can be compared to those of fluids from other wells to measure reservoir connectivity. Such measurements can be the basis for formulating multi-billion dollar production strategies and recovery assessments, so accuracy and reliability are key concerns.
It is noted that the drawings and detailed description are directed to specific illustrative embodiments of the invention. It should be understood, however, that the illustrated and described embodiments are not intended to limit the disclosure, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the appended claims.